This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Military veterans, Norwich cadets, and Middlebury undergraduates will be recruited to participate in a study of threat perception. Participants will be asked to view images and listen to stimuli that vary with respect to their threatening content while eye movements and brain activity are recorded. The auditory stimuli will consist of novel and unexpected sounds. The visual stimuli will include images of middle-eastern men dressed in traditional or nontraditional clothing. Measures of eye movements such as fixation duration, fixation location, and gaze duration will be recorded with eye tracking equipment in order to assess threat related differences in visual attention. Electrical activity in the brain will be recorded using event related potentials (ERPs), which capture the brain's response to specific visual and auditory stimuli. The data will be analyzed for differences in brain activity and eye movement patterns across participants having different levels of military and combat experience. Clinical measures of post-traumatic stress will also be correlated with measures of eye movements and brain activity while viewing threatening stimuli. The goal of this research is to understand how experiences such as cadet training and/or combat exposure affect the underlying attentional mechanisms in the brain that guide the perception of threat.